More than likely you've already herd this by now, but in case you haven't... SWTOR is going Free-to-Play later on this year.

I've played a lot of FtP MMO's in the past and I can say that sometimes the restrictions are pretty annoying. City of Heroes won't let you join a guild or send whispers or friend people unless they are already friend-ed to you, Age of Conan severely limits your bank and pack space as well as funds available to you, just to site some examples. So if your thinking about dropping down to the FtP model, I suggest really assessing what you want outta SWTOR and what sort of restrictions are involved.